Before you head to Sinnoh, it might be a wise idea to pack some headgear to endure its frigid weather. Much like Pikachu, who’s all ready to go with Ash’s Sinnoh Cap from Pokémon the Series: Diamond and Pearl.

To claim your Sinnoh Cap Pikachu, key in the password V0LTTACKLEP1KA via Mystery Gift in Pokémon Sword and Shield.

Here are the full steps to add Sinnoh Cap Pikachu to your party:

1. Launch your Pokémon Sword or Pokémon Shield game.
2. Navigate to Mystery Gift on the X menu.
3. Press Get a Mystery Gift.
4. Press Get with Code/Password and ensure that you are connected to the internet.
5. Enter the password V0LTTACKLEP1KA
6. Save your game.

Sinnoh Cap Pikachu is the fourth of eight special Pikachu scheduled to be released in celebration of the upcoming Pokémon Sword and Shield’s DLC, The Crown Tundra, set to release Oct. 22. Each of the Electric Mouse Pokémon will sport one of his trainer’s quintessential caps throughout the timeline of the anime.

Source: https://dotesports.com/pokemon/news/how-to-get-sinnoh-cap-pikachu-in-pokemon-sword-and-shield